1. Field of the Invention
This invention relates to a method of treating foodstuffs to prevent microbial activity. More particularly, the invention relates to treating the surface of a foodstuff with an antimicrobialy effective amount of a compound to remove, retard of reduce microbial contamination and/or growth without causing substantial organoleptic depreciation of the foodstuff. In an alternative embodiment, the compound may be mixed with the foodstuff to retard or prevent microbial growth. The method may be employed with any foodstuff including meat, fish, vegetables, powdered meat and vegetable stocks, powdered milk, and mixtures thereof.
2. Brief Description of Related Art
"Food preservation", as that term is used herein, includes methods which guard against food poisoning as well as methods which delay or prevent food spoilage due to microbes. Food preservation keeps food safe for consumption and inhibits or prevents nutrient deterioration or organoleptic changes causing food to become less palatable.
"Food spoilage", as that term is used herein, includes any alteration in the condition of food which makes it less palatable including changes in taste, smell, texture or appearance. Spoiled food may or may not be toxic.
"Food poisoning", as that term is used herein, refers to mammalian disease caused by ingestion of food contaminated by pathogenic viruses, molds or bacteria and/or their toxins. Pathogen-contaminated food does not necessarily show any organoleptic sign of spoilage. For example, bacterial food poisoning may be caused by either infection of the host by the bacterial organism or by action of a toxin produced by the bacteria either in the food or in the host.
Prevention of food spoilage and food poisoning has been attempted throughout history often through trial and error. The early attempts have resulted in the adoption of such food preservation methods as the drying, salting and/or smoking of foods in order to preserve them. It has been relatively recent in recorded history that food preservation has been placed upon a scientific foundation. In the nineteenth century, work of such scientists as Louis Pasteur and Robert Koch elucidated the bacterial causes of food poisoning and spoilage and provided new methods of identifying pathogenic bacteria and of preserving food.
Present food technologists utilize an array of physical, chemical, and biological processes and agents to preserve food and prevent the transmission of disease via foodstuffs. In addition to such processes as irradiation, fermentation, pasteurization, control of temperature, pH and/or water activity, a plethora of chemical agents exist. These agents include antioxidants to prevent chemical degradation of food, as well as compounds which kill or inhibit deleterious bacteria and/or other microbes thereby preserving food i.e. preventing both spoilage and the transmission of disease. Commonly employed antimicrobial chemical agents include nitrites, nitrates, sulphur dioxide, sulfites, and acids such as acetic, propionic, lactic, benzoic, and sorbic acid and their salts, wood smoke and liquid smoke, and antibiotics such as natamycin and nisin.
Prevention of food poisoning is of paramount importance in the food processing industry. Concern for food safety has led most countries to heavily regulate the food industry to ensure public health. Also, manufacturers of processed food invest considerable resources to ensure the safety of their products. Despite these efforts, food poisoning still occurs. Many instances of food poisoning are attributed to bacteria such as Salmonella, Clostridium, and Staphylococcus among others.
Many people eat processed foods after a significant period of time has elapsed from a first cooking or pasteurization by the food manufacturer thereby permitting bacteria introduced by post-pasteurization contamination to grow. Since this food consumption may occur without reheating the processed food to sufficient temperatures for sufficient time to kill any microbes which may have been introduced subsequent to initial cooking, there is a risk of food poisoning. The present invention seeks to ameliorate the aforementioned risk.
This is a particular problem with ground meat. Meat, during and after slaughter, may contain or become contaminated with certain undesirable bacteria such as E. coli (especially E. coli 015:H7), Salmonella, Campylobacter, Listeria, spoilage bacteria, and the like. The meat is processed by removing the hide, eviscerating, cooling and cutting into larger cuts of fresh or cured meat. The fresh meat obtained after evisceration is chilled by hanging the sides of red meat at a temperature usually below 10.degree. C. For example, beef is hung for a considerable period to allow natural enzymes to tenderize the beef. Pork is simply cooled. For certain primal cuts, such as ham, bacon, corned beef and pastrami the cuts are cured by chilling below 10.degree. C. followed by injection of a solution containing salt, nitrite and/or nitrate, sweetener, cure accelerator, one or more polyphosphates, spices and flavorings. The meat is prepared to 105% to 130% of its weight with curing solution. Boxed meat is cut into primal cuts after chilling, vacuum packaged and boxed. In spite of such chilling and curing, microbial activity occurs during processing and after processing of the meat.
Various methods have been developed for preventing microbial activity in meat. For example, U.S. Pat. No. 5,268,185 teaches a process to retard bacterial growth by contacting surfaces with a solution of trialkali orthophosphate having a PH above 11.5.
Bynagte, U.S. Pat. No. 3,705,040 uses phosphates to help remove shrimp from their shells. Sodium orthophosphate at 2-15% with other ingredients can be employed.
Cheng, U.S. Pat. No. 4,683,139 teaches a process for prepackaged fresh meat at retail wherein the shelf life of the meat is increased by treatment with an aqueous solution of an alkali metal salt of certain phosphate compounds, a reducing compound such a ascorbic acid and a sequestering or chelating agent such as citric acid. The phosphate can be an orthophosphate, pyrophosphates, tripolyphosphates and hexametaphosphates.
Szezesniak et al., U.S. Pat. No. 4,075,357, teaches salt combined with a secondary salt selected from alkali metal salts of organic acids and trisodium orthophosphate, polyphosphate, metaphosphate and ultraphosphate. Citrates are preferably combined with sodium chloride. These mixtures are used to control water activity in intermediate moisture cooked food.
U.S. Pat. No. 5,374,433 discloses a method for preserving a food product comprising innoculating the food product with an effective amount of euthygienic, non-pathogenic, non-spoilage bacteria to inhibit the growth of undesired pathogenic and spoilage bacteria.
U.S. Pat. No. 4,247,569 discloses an antibacterial agent comprising one of straight chain saturated dicarboxylic acids or an alkali metal salt thereof or a mixture of 2 or more of said dicarboxylic acids or alkali metal salts thereof. The agent may be used in foodstuffs, such as milk and meat.
Kohl et al., U.S. Pat. No. 3,681,091 teaches treating foods including fish fillet with 10% solutions of medium chain length polyphosphates.
However, there is a disadvantage to the prior art products in that the application of some of these agents may cause alteration of the taste, texture and appearance of the food stuff. Furthermore, some of the treatments require delivery in the aqueous form. Therefore the treatments would not be suitable for use on foodstuffs which are on a powdered form such as a powdered milk, powdered gravy mix, powdered soup and stock mixes and other dehydrated foodstuffs such as fruits, vegetables, meats, and fish. Therefore, there is a need for a method to prevent antimicrobial activity which can be used in a non-aqueous form.
Additionally, many of the prior art treatment use materials which may be expensive and/or not readily available. Fatty acids and monoglycerides are readily available and may be formed during the breakdown of milk products, which is a relatively inexpensive product. Furthermore, while many compounds are able to destroy the envelope and inactivate the bacteria or virus, a large number have toxic side effects in the body. Fatty acids and monoglycerides are normal metabolites in the body, notably formed during the breakdown of milk products. The inventors have discovered that applying compounds comprising fatty acids and/or monoglycerides to the surface of foodstuffs successfully inhibits microbial activity.